1. Field of the Invention
The present invention relates generally to apparatus for protecting farm workers from hazardous materials, and more particularly to a novel ventilating apparatus for reducing the exposure of an equipment operator to fumes emanating from the treated ground or fumigating apparatus drawn by a towing vehicle.
2. Background of the Invention
In the agricultural industry, there is a continual need to eradicate and control weeds and soil-borne insects and diseases. One way in which this is accomplished is by means of a process called pre-plant soil fumigation, which has been used for many years with ongoing refinements in methods and techniques to improve efficacy, efficiency and reduce the cost of application.
Chief among the crops which benefit from pre-plant soil fumigation are strawberries, grapes, peppers, onions, deciduous fruits and nuts, turf, cut flowers, and tree and seedling nurseries. The most effective fumigants for crops of the type listed are mixtures of methyl bromide and chloropicrin which are selected in varying ratio and strength, depending on the target soil pest and soil variances of temperature, texture and moisture.
Typically, a field is prepared for fumigation by the grower who tills and irrigates the soil to ensure proper texture and moisture. A commercial fumigator then enters the field with a tractor and tool bar mounted to the rear, to which are attached plumbed shanks that penetrate the soil and deliver the fumigant to the desired depth. Depending on desired effects, the field may be tarped with a polyethylene film which is applied by a roller attached to the tractor. The field is normally ready for planting thereafter within two weeks.
Soil preparation, type and amount of fumigant, and method of application are all part of a process which is regulated by the U.S. EPA and CAL EPA through pesticide labeling laws. One of the concerns associated with the process is worker exposure to the pesticides that may occur through contact or inhalation. For methyl bromide/chloropicrin mixtures, inhalation is the typical route of exposure and over a period of years, has been regulated downwardly.
Current laws allow a single limit exposure and a time-weighed eight hour exposure limit of 5 ppm of methyl bromide in air. Soon to be enacted by CAL EPA and U.S. EPA are rules that will lower the allowed exposure levels even further.
As measured by field monitoring, current exposure levels experienced by the equipment operator are in the range of 0-2 ppm. These levels, though well within limits under current rules, will not be allowed under the proposed new rules.